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Abstract

Middle-aged women have stiffer carotid arteries than men. Parity has been shown to have a J-shaped association with future clinical cardiovascular disease (CVD) events. It is not known whether previous pregnancy related circulatory and metabolic changes are associated with later vascular effects such as decreased distensibility. We examined the association of carotid distensibility with ever being pregnant, and with the number of pregnancies or live births among ever pregnant women.

Methods: We used baseline data from 3322 women free of CVD (aged 45-84 years , 38% Caucasian, 12% Chinese-American, 29% African-American, 22% Hispanic-American) enrolled in the MESA, a population based NHLBI cohort study. Participants answered reproductive history questionnaires. Ultrasound derived carotid artery lumen diameters and brachial artery blood pressures were measured at peak-systole and end-diastole. We estimated carotid distensibility as the 2*slope (diastolic to systolic) of the arterial diameter versus pressure (diastolic to systolic) in mixed models where each individual’s intercept (average carotid diameter) and slope were modeled as random effects, and were adjusted for age, race, height, diabetes, current smoking, HDL-cholesterol and total cholesterol levels.

Results: Of the 2905 ever-pregnant women (87% of total), the median (interquartile range) of pregnancies was 3 (2-5), and of live births was 2 (2-4). In adjusted models, carotid artery distensibility was 17.6×10-5/mmHg lower (p = 0.001, lower distensibility equivalent to 3.6 years of greater age) in ever-pregnant women as compared to never-pregnant women. Among women that were ever pregnant, the distensibility was not significantly different for every additional pregnancy (-7.82×10-6/mmHg/pregnancy, p=0.31), or for every additional live birth (-1.21×10-5/mmHg/live birth, p=0.17).

Conclusion: This cross-sectional study supports the hypothesis that pregnancy results in long term effects on the mechanical properties of arteries. In contrast to studies evaluating CVD events, the association with distensiblity does not increase with greater parity and nulliparity. This result must be confirmed by longitudinal observations in women before and after first and later pregnancies.